/*
 * libunbound/worker.h - worker thread or process that resolves
 *
 * Copyright (c) 2007, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * \file
 *
 * This file contains the worker process or thread that performs
 * the DNS resolving and validation. The worker is called by a procedure
 * and if in the background continues until exit, if in the foreground
 * returns from the procedure when done.
 */
#ifndef LIBUNBOUND_WORKER_H
#define LIBUNBOUND_WORKER_H
#include "util/data/packed_rrset.h"
struct ub_val_ctx;
struct ub_val_result;
struct module_env;
struct comm_base;
struct outside_network;
struct ub_randstate;
struct ctx_query;
struct outbound_entry;
struct module_qstate;
struct comm_point;
struct comm_reply;
struct libworker_res_list;
struct regional;

/** 
 * The library-worker status structure
 * Internal to the worker.
 */
struct libworker {
	/** every worker has a unique thread_num. (first in struct) */
	int thread_num;
	/** context we are operating under */
	struct ub_val_ctx* ctx;

	/** is this the bg worker? */
	int is_bg;
	/** is this a bg worker that is threaded (not forked)? */
	int is_bg_thread;

	/** copy of the module environment with worker local entries. */
	struct module_env* env;
	/** the event base this worker works with */
	struct comm_base* base;
	/** the backside outside network interface to the auth servers */
	struct outside_network* back;
	/** random() table for this worker. */
	struct ub_randstate* rndstate;
	
	/** commpoint to listen to commands */
	struct comm_point* cmd_com;
	/** are we currently reading a command, 0 if not, else bytecount */
	size_t cmd_read;
	/** size of current read command, may be partially read */
	uint32_t cmd_len;
	/** the current read command content, malloced, can be partially read*/
	uint8_t* cmd_msg;

	/** commpoint to write results back */
	struct comm_point* res_com;
	/** are we curently writing a result, 0 if not, else bytecount into
	 * the res_list first entry. */
	size_t res_write;
	/** list of outstanding results to be written back */
	struct libworker_res_list* res_list;
	/** last in list */
	struct libworker_res_list* res_last;
};

/**
 * List of results (arbitrary command serializations) to write back
 */
struct libworker_res_list {
	/** next in list */
	struct libworker_res_list* next;
	/** serialized buffer to write */
	uint8_t* buf;
	/** length to write */
	uint32_t len;
};

/**
 * Create a background worker
 * @param ctx: is updated with pid/tid of the background worker.
 *	a new allocation cache is obtained from ctx. It contains the
 *	threadnumber and unique id for further (shared) cache insertions.
 * @return 0 if OK, else error.
 *	Further communication is done via the pipes in ctx. 
 */
int libworker_bg(struct ub_val_ctx* ctx);

/**
 * Create a foreground worker.
 * This worker will join the threadpool of resolver threads.
 * It exits when the query answer has been obtained (or error).
 * This routine blocks until the worker is finished.
 * @param ctx: new allocation cache obtained and returned to it.
 * @param q: query (result is stored in here).
 * @return 0 if finished OK, else error.
 */
int libworker_fg(struct ub_val_ctx* ctx, struct ctx_query* q);

/** cleanup the cache to remove all rrset IDs from it, arg is libworker */
void libworker_alloc_cleanup(void* arg);

/**
 * Worker service routine to send udp messages for modules.
 * @param pkt: packet to send.
 * @param addr: where to.
 * @param addrlen: length of addr.
 * @param timeout: seconds to wait until timeout.
 * @param q: wich query state to reactivate upon return.
 * @param use_tcp: true to use TCP, false for UDP.
 * @return: false on failure (memory or socket related). no query was
 *      sent.
 */
int libworker_send_packet(ldns_buffer* pkt, struct sockaddr_storage* addr,
        socklen_t addrlen, int timeout, struct module_qstate* q, int use_tcp);

/**
 * Worker service routine to send serviced queries to authoritative servers.
 * @param qname: query name. (host order)
 * @param qnamelen: length in bytes of qname, including trailing 0.
 * @param qtype: query type. (host order)
 * @param qclass: query class. (host order)
 * @param flags: host order flags word, with opcode and CD bit.
 * @param dnssec: if set, EDNS record will have DO bit set.
 * @param addr: where to.
 * @param addrlen: length of addr.
 * @param q: wich query state to reactivate upon return.
 * @return: false on failure (memory or socket related). no query was
 *      sent.
 */
struct outbound_entry* libworker_send_query(uint8_t* qname, size_t qnamelen,
        uint16_t qtype, uint16_t qclass, uint16_t flags, int dnssec,
        struct sockaddr_storage* addr, socklen_t addrlen,
        struct module_qstate* q);

/** process incoming replies from the network */
int libworker_handle_reply(struct comm_point* c, void* arg, int error,
        struct comm_reply* reply_info);

/** process incoming serviced query replies from the network */
int libworker_handle_service_reply(struct comm_point* c, void* arg, int error,
        struct comm_reply* reply_info);

/** handle control command coming into server */
int libworker_handle_control_cmd(struct comm_point* c, void* arg, 
	int err, struct comm_reply* rep);

/** handle opportunity to write result back */
int libworker_handle_result_write(struct comm_point* c, void* arg, 
	int err, struct comm_reply* rep);

/**
 * Write length bytes followed by message.
 * @param fd: the socket to write on. Is nonblocking.
 * 	Set to blocking by the function,
 * 	and back to non-blocking at exit of function.
 * @param buf: the message.
 * @param len: length of message.
 * @param nonblock: if set to true, the first write is nonblocking.
 * 	If the first write fails the function returns -1.
 * 	If set false, the first write is blocking.
 * @return: all remainder writes are nonblocking.
 * 	return 0 on error, in that case blocking/nonblocking of socket is
 * 		unknown.
 * 	return 1 if all OK.
 */
int libworker_write_msg(int fd, uint8_t* buf, uint32_t len, int nonblock);

/**
 * Read length bytes followed by message.
 * @param fd: the socket to write on. Is nonblocking.
 * 	Set to blocking by the function,
 * 	and back to non-blocking at exit of function.
 * @param buf: the message, malloced.
 * @param len: length of message, returned.
 * @param nonblock: if set to true, the first read is nonblocking.
 * 	If the first read fails the function returns -1.
 * 	If set false, the first read is blocking.
 * @return: all remainder reads are nonblocking.
 * 	return 0 on error, in that case blocking/nonblocking of socket is 
 * 		unknown. On EOF 0 is returned.
 * 	return 1 if all OK.
 */
int libworker_read_msg(int fd, uint8_t** buf, uint32_t* len, int nonblock);

/** 
 * fill result from parsed message, on error fills servfail 
 * @param res: is clear at start, filled in at end.
 * @param buf: contains DNS message.
 * @param temp: temporary buffer for parse.
 * @param msg_security: security status of the DNS message.
 *   On error, the res may contain a different status 
 *   (out of memory is not secure, not bogus).
 */
void libworker_enter_result(struct ub_val_result* res, ldns_buffer* buf,
	struct regional* temp, enum sec_status msg_security);

#endif /* LIBUNBOUND_WORKER_H */